documentation: 'git-mailsplit --keep-cr' is not hidden anymore

So far this was an internal mechanism for rebase, but we will be exposing
it to the end users.

Signed-off-by: Stefan-W. Hahn <stefan.hahn@s-hahn.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-mailsplit.txt

@@ -7,7 +7,7 @@ git-mailsplit - Simple UNIX mbox splitter program
 
 SYNOPSIS
 --------
-'git mailsplit' [-b] [-f<nn>] [-d<prec>] -o<directory> [--] [<mbox>|<Maildir>...]
+'git mailsplit' [-b] [-f<nn>] [-d<prec>] [--keep-cr] -o<directory> [--] [<mbox>|<Maildir>...]
 
 DESCRIPTION
 -----------
@@ -43,6 +43,9 @@ OPTIONS
 	Skip the first <nn> numbers, for example if -f3 is specified,
 	start the numbering with 0004.
 
+--keep-cr::
+	Do not remove `\r` from lines ending with `\r\n`.
+
 Author
 ------
 Written by Linus Torvalds <torvalds@osdl.org>

builtin-mailsplit.c

@@ -10,7 +10,7 @@
 #include "strbuf.h"
 
 static const char git_mailsplit_usage[] =
-"git mailsplit [-d<prec>] [-f<n>] [-b] -o<directory> [<mbox>|<Maildir>...]";
+"git mailsplit [-d<prec>] [-f<n>] [-b] [--keep-cr] -o<directory> [<mbox>|<Maildir>...]";
 
 static int is_from_line(const char *line, int len)
 {